A number of patents and publications are cited herein in order to more fully describe and disclose the invention and the state of the art to which the invention pertains. Each of these references is incorporated herein by reference in its entirety into the present disclosure, to the same extent as if each individual reference was specifically and individually indicated to be incorporated by reference.
Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise,” and variations such as “comprises” and “comprising,” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.
It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a pharmaceutical carrier” includes mixtures of two or more such carriers, and the like.
Ranges are often expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment.
This disclosure includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Rheumatoid Arthritis
Rheumatoid arthritis (RA) is a chronic inflammatory disease characterised by painful swelling, stiffness, loss of movement and the destruction of cartilage and bone. RA is characterised by an inflammation of the synovial lining of multiple joints and commonly affects the joints of the wrist and hands and may also affect the elbows, shoulders, hips, neck and knees; the ultimate hallmark of RA is joint destruction. RA is a common disease, estimated to affect up to 1% of adults in the developed world, with women more than twice as likely to be affected and over 30% of patients likely to become severely disabled within 20 years (see, e.g., Feldmann et al., 2006). RA is one of the most important causes of disability in the western world and is associated with a significant reduction in quality of life as well as increased mortality if left untreated. The disease can start at any age, with individuals aged between 40 and 70 most commonly affected.
The exact cause of RA remains unclear, but is highly complex and may involve the combination of a number of factors which lead to the development of autoantibodies, formation of immune complexes, production of pro-inflammatory cytokines, angiogenesis and eventual bone and cartilage loss (see, e.g., Klareskog et al, 2006; Ziff et al, 1990; Weissmann et al, 2006; Firestein et al, 2005). These factors include an abnormal immune response caused by reduced self tolerance or a biological trigger such as reaction to environmental factors, infectious agents, or hormonal stimulus (see, e.g., Klareskog et al, 2006); antibodies to the Fc fragment of IgG, known as rheumatoid factor, are present in 60-80% of adults with RA (see, e.g., Weissmann et al, 2006) but it is not known whether this factor is responsible for initiating the inflammatory cascade or is generated at a later stage and propagates the process (see, e.g., Weissmann et al, 2006); there is also a notable genetic predisposition to the disease, as shown by the presence of HLA-DR4 antibody in 70% of patients (see, e.g., Klareskog et al, 2006). At the cellular level, development of RA usually commences with T-cells infiltrating the synovial membrane lining the affected joint; this then leads to the activation of macrophages, monocytes and synovial fibroblasts (see, e.g., Firestein, 1996) by way of cell-cell contact and release of various cytokines, including TNFα and IL-1 (see, e.g., Feldmann, 1996). Activation of these cells leads to the overproduction of a range of pro-inflammatory cytokines, of which the most important are TNFα, IL-1 and IL-6 (see, e.g., Brennan et al, 1996; McInnes et al, 2005). These pro-inflammatory cytokines are then instrumental in orchestrating several complex signal transduction cascades, including the NFκB, MAPK and Jak/STAT pathways (see, e.g., Firestein et al, 1999) which lead to the induction of genes coding for various products that propagate the inflammatory response and also promote tissue destruction. These products include tissue-degrading enzymes such as collagenases, matrix metalloproteases, cathepsins, and other pro-inflammatory factors such as selectins, integrins, leukotrienes, prostaglandins, chemokines, and other cytokines. Furthermore, TNFα and IL-1 also induce RANKL expression.
RANKL is an essential factor for the generation of osteoclasts (see, e.g., Tanaka et al, 2003; Roodman, 2006), and upregulated RANKL-production leads to increased osteoclast differentiation and ultimately bone destruction (see, e.g., Tanaka et al, 2003; Roodman, 2006). The inflammatory response leads to the accumulation of many leukocytes and immune factor populations within the affected joint and also to hyperplasia of the Type-A and Type-B synoviocytes (see, e.g., Firestein et al, 2005), leading to thickening and vascularisation of the synovium into a destructive and aggressive tissue known as a pannus. The pannus contains both osteoclasts, which destroy bone, and metalloproteases, which continue the destruction of cartilage.
Treatment of Rheumatoid Arthritis
Early therapies for RA focussed on controlling the symptoms of the disease, mainly by reduction of inflammation, rather than retarding disease progression. These drugs included NSAIDs such as aspirin, diclofenac and naproxen and, until recently, the COX-2 selective drugs Celebrex® and Vioxx® were also widely used. Inflammation was further controlled by glucocorticoids, and their combination with NSAIDs provided reasonably effective short-term control of the inflammation. More recently, a more aggressive approach to treating RA has been introduced starting at disease onset, using so-called disease-modifying anti-rheumatic drugs (DMARDs), which act to slow or even prevent disease progression. These include a number of older drugs, including gold salts; sulfasalazine; antimalarials such as hydroxychloroquine; D-penicillamine; immunosuppressants such as mycophenolic acid, azathioprine, cyclosporine A, tacrolimus and sirolimus; minocycline; leflunomide; and most importantly, methotrexate (see, e.g., Smolen et al, 2003).
Methotrexate is now the gold-standard therapy for clinical trial comparisons, and is generally used in combination with newer therapies. It is effective in most patients but, in common with all of the above agents, has significant gastrointestinal side effects, which lead to roughly 50% of patients eventually having to cease treatment with methotrexate (see, e.g., Mount et al, 2005). A further drawback of these older DMARDs is the length of time taken for the drug to start acting, ranging from weeks with methoxtrexate, to months with gold salts. Whilst full remissions only occur in about a quarter of patients, for those showing no effect it is not generally possible to stop therapy without suffering the risk of a more violent disease rebound (see, e.g., Smolen et al, 2003). In recent years, the treatment of RA has been revolutionised by the advent of biological agents which target specific inflammatory pathways. The first and most important of these are the anti-tumour necrosis factor (anti-TNF) agents (see, e.g., Elliott et al, 1994).
The Role of TNFα in RA
As discussed above, the TNF superfamily of receptors and ligands plays a key role in the causation of inflammation and associated local and systemic bone loss. TNFα production within the joint may in fact play the pivotal role in orchestrating the production of other factors which leads to the persistence of inflammation and tissue damage (see, e.g., Feldmann et al, 2001; Brennan et al, 1999; Brennan, 1992). The importance of TNFα in RA is highlighted by the finding that antibodies blocking TNFα can prevent inflammation in animal models of RA, and that anti-TNFα therapy is currently the most effective treatment for RA (see, e.g., Elliott et al, 1994; Feldmann et al, 1994; Joosten et al 1996, Klareskog et al, 2006). However, there is evidence that there are some TNFα-independent effects of IL-1 in RA, most notably bone destruction (see, e.g., van den Berg et al, 1999; van den Berg et al, 2002).
TNFα is a cytokine that effects many different functions, including the alteration of tissue remodelling, changes to the permeability of the epithelial cell barrier, activation of macrophages, up-regulation of adhesion molecules, recruitment of other immune response effectors and, most importantly in RA, it instigates the signalling cascade which leads to the activation of the transcription factors NFκB and AP-1 (see, e.g., Liu, 2005; Baud et al, 1999). Binding of TNFα and IL-1 to their respective receptors leads to the recruitment of downstream signal transducers called TRAFs. Further kinases are recruited by the TRAFs, and the resulting kinase complex activates the MAP-kinase pathway, ultimately leading to activation of AP-1, and the phosphorylation of IκB kinase. IκB is the inhibitor of NFκB, which acts by preventing translocation of NFκB to the nucleus. Phosphorylation of IκB by IκB kinase leads to degradation of IκB. Once IκB has been degraded, NFκB migrates to the nucleus, where it promotes transcription of anti-apoptotic genes, which promote survival of T and B-cells, thereby prolonging the immune response. This prolongation of the inflammatory response is central to the chronic nature of RA. The importance of NFκB activation is demonstrated by the fact that inhibition of NFκB activity by inhibitory peptides can prevent arthritis in animal models of RA (see, e.g., Jimi et al, 2004).
Anti-TNFα Therapy
Anti-TNFα therapy represents the market-leading therapies for RA, and is performed either with neutralising antibodies such as infliximab (Remicade® J&J and Schering Plough) and adalimumab (Humira®, Abbott) or decoy receptors such as etanercept (Enbrel® Amgen and Wyeth), both which represent validated and highly effective treatments for RA. Anti-TNFα biologicals are already licensed for RA, Crohn's disease, and psoriasis. A number of other inflammatory and autoimmune disorders are also being investigated as potential targets. Other approaches to blocking the action of TNFα include the pegylated anti-TNFα fragment certolizumab (Cimzia®, UCB); inhibition of proximal signalling intermediates such as MAP kinase; interference with the synthesis of TNFα via inhibition of TNFα converting enzyme (TACE); and inhibition of the metalloproteases responsible for cleaving TNFα from the cell surface (see, e.g., Smolen et al, 2003; Mount et al, 2005).
Other Inhibitors of NFκB Activation
As described above, the binding of IL-1 and RANKL to their receptors also initiates a signalling cascade, which eventually leads to the activation of NFκB and subsequent inflammatory response. The efficacy of inhibitors of these ligands has been validated by the use of the IL-1 receptor antagonist anakinra (Kineret® Amgen) for the treatment of RA, and the completion of clinical trials for the monoclonal antibody against RANKL AMG-162 (Denosumab® Amgen) for osteoporosis (it is also in clinical trials for RA and psoriasis).
Other Common Inflammatory Diseases Mediated by TNFα
There are several other common inflammatory diseases in which TNFα has been shown to play a major role and in which TNFα inhibitors have found therapeutic use. These include inflammatory bowel disease (IBD) and psoriasis.
IBD is an inflammatory disorder of the gut affecting about 0.25% of the population in the western world, of which the two main forms are: ulcerative colitis (UC), in which the lining of the colon becomes inflamed and ulcerated; and Crohn's disease (CD), which can occur anywhere within the gastrointestinal tract, but most often the ileum, and commonly involves inflammation of the entire gut wall. Common symptoms of IBD are bloody diarrhea and abdominal pain.
Psoriasis is an inflammatory response of the skin affecting 1-3% of the population in the western world. The disease is characterised by raised, red, scaly plaques on the skin, which may be itchy and also cause significant psychological distress by their unsightly nature. A further complication of psoriasis is the development of psoriatic arthritis, an inflammatory arthritis of the joints, in up to 40% of patients, which develops on average 10 years after the first symptoms of skin disease are seen (see, e.g., Gottlieb, 2005).
As with RA, the aetiology of IBD and psoriasis are unknown and may involve a complex combination of infectious agents, environmental, and genetic factors, generating an inappropriate and prolonged inflammatory response.
Treatment of IBD and psoriasis has followed a similar pattern to that of RA, with the past use of immunoregulatory agents such as NSAIDs, methotrexate, cyclosporine, steroids, and antimetabolites such as 6-mercaptopurine for IBD (see, e.g., Korzenik et al, 2006) and methotrexate and cyclosporine for psoriasis (see, e.g., Gottlieb, 2005). The treatment of both has been revolutionised by the advent of biological agents, in particular those which block TNFα signalling. Etanercept is licensed for the treatment of psoriasis and psoriatic arthritis; both infliximab and adalimumab are licensed for psoriatic arthritis, IBD, and psoriasis.
Cancer
There is growing evidence that activation of NFκB can play a major role in the promotion and progression of both haematological malignancies, such as myeloma and lymphomas, and solid tumours, such as breast, prostate and lung cancer (see, e.g., Baud and Karin, 2009). There is also rising awareness of the role and importance of inflammation in cancer and in the development of resistance to radiotherapy and to chemotherapeutic agents, and it has been suggested that inflammation is in fact one of the basic hallmarks of cancer (see, e.g., Mantovani, 2009). Improving the efficacy of anti-cancer treatments by prevention of NFκB activation is therefore a promising strategy to augment existing therapeutic regimes and is currently under investigation, most notably for the treatment of multiple myeloma.
Defects in the normal apoptotic pathways are also implicated in the development and progression of tumour cell growth. Apoptosis (programmed cell death) plays a key role in the removal of abnormal cells; defects in the signalling cascades, which would normally lead to its induction, play a key role in oncogenesis. Radiotherapy and many chemotherapeutic agents act by causing cellular damage, which would normally induce apoptosis; defects in the pathway will therefore also reduce the effectiveness of such agents. The most important effector molecules in the signalling pathway leading to apoptosis are known as the caspases, which may be triggered by a number of stimuli, including TNFα binding to its receptor. Mutations in the genes which encode for the caspases have been found in a number of tumour types, including gastric, breast, renal cell and cervical cancers as well as commonly in T-cell lymphoblastic lymphoma and basal cell ameloblastomas (see, e.g., Philchenkov et al., 2004). Compounds which activate caspases, and thus sensitise cells to apoptosis, would be highly effective as cancer therapies either as single agents or in enhancing the effectiveness of existing cancer chemotherapy and radiotherapy.
Common Bone Diseases
Osteoporosis is a common disease characterised by reduced bone density, deterioration of bone tissue, and an increased risk of fracture. Many factors contribute to the pathogenesis of osteoporosis including poor diet, lack of exercise, smoking, and excessive alcohol intake. Osteoporosis may also arise in association with inflammatory diseases such as rheumatoid arthritis, endocrine diseases such as thyrotoxicosis, and with certain drug treatments such as treatment with glucocorticoids. However one of the most important factors in the pathogenesis of osteoporosis is heredity.
Paget's disease of bone is a common condition of unknown cause, characterised by increased bone turnover and disorganised bone remodelling, with areas of increased osteoclastic and osteoblast activity. Although Pagetic bone is often denser than normal, the abnormal architecture causes the bone to be mechanically weak, resulting in bone deformity and increased susceptibility to pathological fracture.
Many types of cancer affect bone. Cancer-associated bone disease can be manifest by the occurrence of hypercalcaemia or the development of osteolytic and/or osteosclerotic metastases. Increased osteoclastic bone resorption plays a key role in the pathogenesis of both conditions. Whilst almost any cancer can be complicated by bone metastases, the most common sources are multiple myeloma, breast carcinoma, and prostate carcinoma. The most common tumours associated with hypercalcaemia are multiple myeloma, breast carcinoma, and lung carcinoma.
RANKL signalling has been shown to play a major role in osteoclast over-activity and a consequent increase in bone loss (see, e.g., Tanaka et al, 2003; Roodman, 2006). The use of drugs which affect this pathway has been validated by the completion of clinical trials of the monoclonal antibody against RANKL AMG-162 (Denosumab® Amgen) for the treatment of osteoporosis/multiple myeloma.
As described previously, bone loss also plays a major role in the pathophysiology of rheumatoid arthritis and drugs which prevent activation of the signalling pathways described (e.g. TNFα blockers) are also able to prevent this bone loss.
Agents that Prevent Inflammation and/or Bone Loss
The inventors have identified a new class of compounds which, for example, prevent inflammation and/or bone loss, and thus may be used in the treatment of diseases with an inflammatory or autoimmune component, including, for example, rheumatoid arthritis, inflammatory bowel disease, psoriasis, and psoriatic arthritis; diseases which involve bone loss, including, for example, bone loss associated with rheumatoid arthritis, osteoporosis, Paget's disease of bone, and multiple myeloma; as well as cancer associated with activation of NFκB, with aberrant NFκB signaling, or with inflammation, including haematological malignancies such as multiple myeloma, leukaemia, T-cell lymphoblastic lymphoma, and other lymphoma (e.g., non-Hodgkin Lymphoma), and solid tumours such as cancer of the bladder, breast cancer (female and/or male), colon cancer, kidney cancer, lung cancer, pancreatic cancer, prostate cancer, brain cancer, skin cancer, thyroid cancer, and melanoma; and cancer associated with the inactivation or impairment of caspase-mediated cell death, such as gastric cancer, breast cancer, renal cancer, cervical cancer, and basal cell ameloblastomas.
Without wishing to be bound by any particular theory, the inventors believe that this action may be via a mechanism that involves blocking TNFα and/or IL-1 and/or RANKL-signalling.
Biphenyl Sulfonamides
Greig et al., 2004 and Greig et al., 2006 describe a class of biphenyl alkyl sulfonamides as anti-resorptive agents for the treatment of bone diseases, including, for example, 2′,4′-difluoro-biphenyl-4-sulfonic acid (5-hydroxy-pentyl)-amide (ABD248) and 2′,4′-difluoro-biphenyl-4-sulfonic acid (4-hydroxy-butyl)-amide (ABD256) (shown below).

Greig et al., 2008 (not yet published), describes a class of biphenyl alkyl sulfonamides, as anti-resorptive agents for the treatment of bone diseases including, for example, 2′,4′-difluoro-biphenyl-4-sulfonic acid (3-hydroxymethyl-phenyl)-amide (ABD456), 2′,4′-difluoro-biphenyl-4-sulfonic acid (4-hydroxymethyl-phenyl)-amide (ABD466), and 2′,4′-difluoro-biphenyl-4-sulfonic acid [3-(2-hydroxy-ethyl)-phenyl]-amide (ABD628), shown below.

It appears that compounds of the following formulae may be known:
No.StructureRegistry No.11022865-56-9 2313238-50-5
The present inventors have identified a new a class of aryl sulfonamides, as defined herein, that have surprising and unexpected properties.
The present inventors have identified a new a class of aryl sulfonamides, as defined herein, that have, inter alia, one or more surprising and unexpected properties.
Without wishing to be bound to any particular theory, the inventors believe that the new compounds have been protected against the major route of metabolism acting upon the previous biphenyl aryl sulfonamides (specifically, oxidation of the terminal alcohol to give a carboxylic acid) by the addition of a suitable blocking group in this region. In addition to the resulting substantial improvement in metabolic stability, these blocking groups have also been selected to provide a further substantial enhancement in the aqueous solubility of the compounds. If a drug is to show oral activity, it must first be solvated, to permit absorption from the gastrointestinal tract. Second, the drug must be sufficiently resistant to first pass metabolism by metabolic enzymes contained within the liver so as to be able to enter the circulation and permit sufficient quantities to reach the biological target. Third, the drug must be sufficiently potent against the biological target to give the desired therapeutic effect.
The optimization of pharmacokinetic properties (action of the body on the drug) of a drug is a developmental barrier of equal challenge as compared to the optimization of pharmacodynamic properties (action of the drug on the body). By improving both solubility and stability, with little or no loss of potency against the biological target, the new compounds disclosed herein show substantial improvements in their properties as oral therapeutic agents, as compared to previous compounds identified above. The new compounds combine the characteristics required of orally active agents for the treatment of inflammatory diseases and/or for the treatment of bone loss.